# All Questions

259 views

### Convert logical relational expression to / from disjunctive and conjunctive forms?

I would like to convert logical relational expressions in disjunctive form, e.g., $$(x \lt -1) \lor (-1 \lt x \lt +1) \lor (x \gt +1)$$ into conjunctive form, e.g., $$(x \ne -1) \land (x \ne +1)$$ ...
188 views

### Solving a system consisting of an ODE and a non-differential equation

I would like to solve the following system of equations: y'[t] == x[t]*y[t] - x[t]; 10 == x[t]*y[t]/(x[t] + y[t]) + x[t]/(x[t] + y[t]^2) Is there any way to ...
450 views

### RefProp in Mathematica

RefProp by NIST is a program that calculates the thermodynamic properties of fluids. I need to call certain RefProp functions ...
982 views

### Graphical Plots of PDF and CDF

I have a joint density and distribution function that I want to plot in a meaningful way, (i.e., want to be able to see how the functions behaves as changes in x and y happen simultaneously. If ...
3k views

### Spiral pattern and Fibonacci numbers

I'm want to generate a 2D spiral pattern like the the one shown in the following figure. I can generate the spirals one by one, but I think there ought to be a more efficient method for generating ...
411 views

### Efficiently appending points to a NearestFunction

I have a program which works with a list of points (in 3D, but it could be in 1D as well, it won't make a difference). Within a loop, it keeps adding new points to the list. To calculate the ...
6k views

### Solving a tridiagonal system of linear equations using the Thomas algorithm

I'm trying to write a function that can solve a tridiagonal system of linear equations using the Thomas algorithm. It basically solves the following equation. (Details can be found at the Wiki page ...
157 views

### Version 8.0 integrates but Version 9.0.1 doesn't

I am trying to run the following integral in version 9.0, but it fails: ...
258 views

### Manipulating a Graphics3D output with a large number of geometric primitives

I'm attempting to view and rotate a Graphics3D object with a very large set of geometric primitives ($\approx 10^6$ objects such as spheres or lines), and everything is functioning very slowly. Are ...
2k views

### How to draw a higher-genus surface

NB: By higher-genus surface, I mean a closed orientable surface of genus at least 2. This question has come up before on math.SE, and even MathOverflow, but most posters suggested using either ...
117 views

### How can PixelConstrained be emulated with DensityHistogram?

This DensityHistogram doesn't display very well. Some bins are shown much larger than others and, oddly, empty bins appear to be drawn smaller than occupied bins. ...
1k views

### Exporting a .xlsx file with about 500 columns

When I want to Export["text.xlsx", data] where data is a matrix with 500 columns and 10000 rows, I get the error message: ...
77 views

### How to define the tangent gradient operator? [duplicate]

I would like to define a new differential operator that is the tangent gradient for a curve $\Sigma$. This is defined as $$\nabla_\Sigma=\mathbf{P}\nabla$$ where $\mathbf{P}$ is the projection ...
81 views

### SetDelayed and avoiding function calls through memoization [duplicate]

I am fairly new to Mathematica. I am working my way through a number of books. I have been looking at the use of SetDelayed and want to confirm that my ...
190 views

### Problem when merging cells including commentary

Bug introduced in 9.0 and fixed in 9.0.1 This is a more of a problem report than a question. When merging the two cells Cell1: foo (*foobar*) bar and ...
1k views

### How to change default settings of cell formatting?

I find font size of Text cells too small and I like displaying them with background colour... I've read this question and learned about ...
207 views

### Solving $k\log(n) - k\log(k) \leq u$

How can I persuade Mathematica to help me find solutions to the inequality $k\ln(n) - k\ln(k) \leq u$ over the reals, assuming $u \geq n \geq k \geq 1$. When I evaluate ...
239 views

### Go to definition of symbol/variable

Is there any easy way of directly jumping to the definition of a Variable like it is implemented in some good IDEs? Currently I have to search manually (ctrl+f) through the whole workbook to find it ...
3k views

### Distribution of random points in 3D space to simulate the Crab Nebula

I'm generating some 3D models of planetary nebulae and supernova remnants for Celestia, a free OpenGL astronomy software. Currently, I know how to do it with random points inside a spherical shell. ...
346 views

### Inconsistent results from equivalent integrals

Why is Mathematica returning different values for these two integrals: I am just being introduced to complex integration, so it's possible that I have a misunderstanding of how this works, but in ...
69 views

### Unique[] in RHS of rule

I have a function, explicit that takes dot product of two symbols, and replaces it with repeated dummy indices generated by ...
104 views

### Graphing the amount of time a function takes

I know I can find out the amount of time a function takes to run like this: In:= function1[100] //Timing Out:= {0.043334, Null} How can I graph this over a set ...
700 views

### A deterministic function to generate a random number

Using Mathematica, I need to define a function of one integer variable that generates the same real number in the range 0 to 1, if it is called with the same argument, but gives a different real ...
2k views

### Plotting with Units

I'm trying to get Mathematica to plot with units, but I'm having some trouble. Below is a minimal example of trying to plot y = x, where ...
249 views

### Does pass-by-value affect the performance of function calls?

I only have a little coding experience in C, and I remember I was told that pass by reference is more efficient than pass by value since the parameters don't need to be copied. Since there is no pass ...
1k views

### OpenCL Dot Product

I have to calculate billions of dot products. My current implementation uses Compile to generate C code and it's very fast (10s ...
240 views

### Weird resampling when I try to export an Image

Mathematica language newbie here. I wrote the following code to quantize an image: ...
3k views

### Contour Plot in Cylindrical Coordinates

I'm trying to render an equation in the cylindrical coordinates, and I used the following codes: ...
127 views

### Strange function definition result [duplicate]

I'm relatively new to Mathematica, and I'm trying to define a function f(k) that would do the following: For any positive integer $k$, a finite sequence $a_i$ of fractions $\frac{x_i}{y_i}$ is ...
920 views

### How can I make points “glow”?

I have a set of points in the plane which I would like to have "glow". I would like for each point to glow individually and I would also like some increase in the intensity corresponding to an ...
296 views

### Problem with large values in ParametricPlot

I've got a question quite similar to No 18163:Problem with high parameter values in ParametricPlot, but the solution of that problem did not work for me. So I hope you may have another tip. I want to ...
357 views

### FindInstance returns Indeterminate in version 9, but not in 8

Bug introduced in 9.0 and fixed in 10.0.0 Here is a trivial system of equations in three unknowns for which FindInstance obtains a solution: ...
2k views

### Mathematica color schemes for the colorblind

Does Mathematica have a graphics option that makes plots intelligible for people with colorblindness?
107 views

### Notation not recursive enough?

My notation is not recursing enough. For example, Notation[W[a_ | b_] ⟹ foo[a_, b_]/foo[b_]] Notation[W[a__, b_ | c_] ⟹ W[a__ | c_]W[b_ | c_]] Then ...
39 views

### Correspondence between eigenvectors and eigenvalues [duplicate]

Let us say I have a matrix h (2x2). Now, I want to get the eigenvectors and eigenvalues of my matrix h: ...
825 views

### Helio chart for canonical correlation

I'm trying to create a chart usually called "Helio chart". It's a chart type very suited for canonical correlation analysis involving several dependent and independent variables. However, it is a ...
1k views

### Copy last/second last (etc.) input from history into current cell

I like to use terminals (e.g. gnome-terminal) where you can use the up key to copy the last command into the current input 'field'. For example, to repeat the last ...
195 views

### How can I create a table of sliders?

I'm trying to do the following: I have a table: w = Table[ToExpression[ToString[h] <> ToString[i]], {i, 1, Length[c]}] This table is suposed to generate ...
129 views

### Controlling margin around PlotLegends

Here's my code: ...
341 views

### How to completely reinstall Wolfram Workbench on linux

I've messed up my Ubuntu install, I've changed some pathnames I shouldn't have (don't know which ones exactly though), and after that Wolfram Workbench was not launching anymore. I uninstalled it by ...
135 views

### Where to find a summary for Q functions? [duplicate]

Is there a summary for all Function like NumberQ, LetterQ and so forth? data=123; IntegerQ[data] True
1k views

### What is the average of rolling two dice and only taking the value of the higher dice roll?

I am referencing to this question on mathunderflow: What is the average of rolling two dice and only taking the value of the higher dice roll? Now I tried: ...
660 views

### Separating positive and negative numbers into two arrays

$c$ is a vector with real numbers.I want to separate the positive ones and the negative ones into two vectors: $a$ and $b$. I have the following problem: When I do: ...
1k views

### Placing bar chart labels on the upper and lower frame axes

In the bar chart (with negative values) ...
491 views

### Solving and plotting ODEs while varying one of the initial conditions

How can I vary an initial condition in the numerical solution of a system of ODEs and then make a 3D plot of the solution space with that condition as one of the variables. ...
224 views

### How can I get all the results from a Wolfram | Alpha query?

When I query Wolfram | Alpha with "city in orange county, california", it returns the first four results with a note that there are "42 total". I can then hit the "more" button until all 42 are ...
2k views

### Labels for each curve on a multi-curve plot using an efficient method(without writing a large code) [duplicate]

I have a question on plot labeling in Mathematica. I have y = 4 x / L + 2 where L = {10, 20, 30, 40} I want to draw a ...
2k views

### How can I make the Cartesian product of a list with itself? [duplicate]

I'm trying to build the table {{1, 1}, {1, 2}, {2, 1}, {2, 2}} given the list {1, 2} I can do it like this ...